Making an Absolute - Process, lessons learned, and recommendations

I'm interested in experimenting with making my own absolutes and was wondering if anyone really had any experience with this. I apologize if this has already been covered, but all I could find was a few tips and vague advice.

I'm not searching to make a particular absolute here, I just want to learn, and would love to start with a couple plants that might be easier to make absolutes from.

So far, most of my research has been towards hexane derived absolutes. What I can't find is the exact process, like how much hexane, is heating necessary, best way to prepare the plant for soaking (i assume dicing is good, but mashing risks forcing out some of oils). Then once you have the concrete, soaking it in ethanol to bring out the oils you want and then distilling the alcohol out (or simply allowing it to evaporate).

Any holes that can be filled in or better explained here would be much appreciated. Also, any recommendations on where to find the right type of hexane for the process (sadly, most info online seems to be marijuana focused, and not exactly the type of resources I want to rely on).

Re: Making an Absolute - Process, lessons learned, and recommendations

I admire your ambition and look forward to reading about the results. Otherwise, I have no experience or advice. I believe that many DIYers use the Steffan Arctander "bible" as a reference. Perhaps you might be able to upload the online copy.

Re: Making an Absolute - Process, lessons learned, and recommendations

I can imagine that it would work on marijuana just as well as any other botanical. Hexane is one of the most commonly used solvents for making concretes but it has a boiling point of 69°C, so the hexane is removed from the concrete with a vacuum pump to minimize the heat needed. Hexane comes in many grades, including food grade. Food grade hexane has had the benzene and toluene removed. Hexane is usually sold as a mixture of related hydrocarbons with similar boiling points, rather than isolated n-hexane.

It is necessary to use enough hexane to fully submerge the plant material. This is to insure that there is full contact with the solvent. The plant material used for making concretes is always fresh and undried. If the material is dense then grinding may be necessary for a full extraction. For a full extraction, the material must be soaked for several hours. The solution is then filtered and evaporated under vacuum.

After the concrete has been produced, it is dissolved in ethanol and refrigerated to around -20°C for 48 hours. This causes the waxes and fats to precipitate, which are then filtered out. The filtration takes place while the solution is still cold, to stop any lipids from redissolving. Lab grade filter paper such as Whatman #1 (11 µm) is sufficient for this purpose. For the home producer, good quality coffee filter paper may work instead.

Finally, the ethanol is removed under vacuum to produce the absolute. If you don't have a vacuum pump or you don't wish to buy one, then it's better to use a refigerant gas (hydrofluorocarbons, butane etc) to make the concrete, which boil off unaided. You can then dissolve the concrete in ethanol and rather than removing the ethanol, use it in solution as you would a tincture. I hope that this answered your questions.

Re: Making an Absolute - Process, lessons learned, and recommendations

Pears has given a splendid answer here already so I'll just caution on the safety aspects of doing this at home: beware that many of these solvents (including ethanol) are highly volatile and can form explosive mixtures with air. Combining these vapours with heat can be a very dangerous business, so please take great care that you know what you are doing and have either a sealed system or spark-proof ventilation or both before you start.

Re: Making an Absolute - Process, lessons learned, and recommendations

It was a good idea to mentioned that, Chris. It's important to follow the necessary safety protocols. Good ventilation is of paramount importance. If needs must, he can set everything up outdoors, weather permitting. Safety gloves would also be important, especially if handling refrigerant gases. I would detail a cheap and simple method for using refrigerant gases like butane but I think that he's more interested in using hexane.

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I should add that sometimes it isn't necessary to convert a concrete into an absolute, it depends on the plant material, the solvent used and the extraction temperature. Some plant materials contain much lower levels of wax than others and don't produce concretes that are particularly waxy. If the solvent is very cold then it will also extract considerably less wax. This is one of the reasons why refrigerant gases are used. The other reason being that no heat or vacuum is required to remove the solvent.

Butaflor is a registered name (P Robertet & Cie) given to a series of highly concentrated perfume materials produced by extraction with butane at subnormal temperatures. The solvent is recovered by evaporation at room temperature (boiling point of butane is -0°.50C). The low extraction temperature and the selected solvent result in a pale-coloured, almost wax free and terpenless product. The method is particularily useful and advantageous when applied to very delicate or heat sensitive botanical materials, e.g. lilac flowers. jasmin, rose, lily of the valley (muguet), orange flowers etc. Certain staple materials are also treated in this method, e.g. ginger rhizomes. It should be kept in mind that not all Butaflors are completely alcohol solvent.

A small home set up could be put together with a vacuum flask (thermos flask), a butane tank (or several butane canisters), some filter papers and a borosilicate glass collection dish. The reason for using a vacuum flask or thermos is that they keep refrigerant gases in liquid phase for several hours, at atmospheric pressure. This is why they are often used in labs to store liquid gases, such as liquid nitrogen.

I'm not suggesting that anyone do this themselves, I'm just describing how it could be done. As Chris stated earlier, it would be necessary to use caution and follow all of the safety protocols. Good ventilation, no ignition sources, protective gloves etc. Butane is highly flammable and for a home set up, it would be safer to evaporated it outdoors. The same would be true for alcohol, ofcourse.

Re: Making an Absolute - Process, lessons learned, and recommendations

I've been meaning to add to this post for some time, but I have just not had the time until now. Already you have several excellent replies from people more qualified than me on many fronts. What I can add is my own experience on making absolutes (actually I only went as far as a concrete, but essentially the same except for the last step) at home using hexane. The short answer is it is both expensive and dangerous to do this, but it is possible. I did it because I was in a place (Burma) where I did not have easy access to absolutes by conventional means and there were some flowers in my garden where absolutes simply did not exist. Also after having tried many other methods such as tincturing and becoming frustrated by the fact water builds up in alcohol when folding tinctures of flowers are made. And hexane was easy to buy. With varying success, I made a concrete of 4 different things: 1) Gardenia, 2) a small indolic flower I don't know the English name of 3) Oakmoss, 4) Frangipani

In all but the case of the Frangipani I used small amounts of hexane (1 liter). For Frangipani I used 5 liters of hexane (and 5 times more flowers). On advice from this forum I proceeded by picking fresh flowers every day putting them in the hexane overnight, draining/filtering the the next day and putting in new flowers in order to saturate the hexane as much as possible. (you need two containers, in order to pour from one to the other and back. I would clean the alternate container completely after each day). This was the main process. I did this without any scientific way of telling them the Hexane was fully saturated. In the case of Gardenia I ran out of flowers as the season was shorter than my patience. The other limiting factor of this method is hexane loss, as some clings to the flowers each time they are discarded. This is unfortunate as you are losing both nice saturated hexane you have worked to hard to get and also the hexane itself, at $10/ Liter was being lost). A solution to this would be squeezing them out, but I wanted as little contact with the hexane as possible so I let the drip, sitting in a funnel, to get as much as possible, but far from ideal. I disposed of the toxic waste spent flowers by laying them out in the sun on the pavement to burn off as much hexane as possible before adding them to the gardener's "to burn" pile of organics. Also of note: some flowers (Gardenia and Frangipani) are quite "fat" and contain a lot of water, and small deposits of water developed in the bottom of the hexane containers. I used a pipette to remove this everyday once I realized it would contaminate the mix with potentially rancid water full of organics. Once complete I filtered the hexane solution through lab filter paper two or three times. The next step would be to run it through a rotary evaporator to both re-capture the hexane for later use and to separate out the concrete at a low boiling temperature. Unfortunately I did not have this. I consulted a friend who used to work in a traditional medicine extracting lab (hoping I could borrow a rotovap) and he said a group of Japanese technicians had the same problem, wanting to extract coffee flower concrete for their personal use. The low tech, and not ideal, solution offered to me was: Get a large beaker (the beaker spout is important as you will see in a moment), boil water far from your hexane and bring the pan to the beaker, now filled with your saturated hexane. Put the beaker in the pan of hot water (as in a double boiler). Put a plate or bowl over the beaker and fill this (plate or bowl) with cold water. Reheat the water as many times as necessary until all the hexane is out. The idea here I think is that the volatiles from the plants will stay mostly in the container and the hexane, being more volatile, will slowly bleed off into the atmosphere through the beaker spout. I did this outside as you can imagine due to the fact Hexane gassing off in the house is not a great idea on many fronts. This method has many drawbacks, from losing nice smelly volatiles, to the whole thing after weeks of work getting knocked over by the dog (or in the case of my garden in Burma, God knows what pythons, palm civets etc.) to the fact without a vacuum you will never really get all the hexane out and traces will remain. It also took an incredible amount of time this way. In the end, running out of patience, I got an extension cord and put the pan of water directly on an electric burner at low power (with the beaker in it still as in a double boiler of course). Nothing blew up (this is no guarantee it might not for you...). When handling Hexane I thought of it as gasoline in terms of danger and volatility. I also found the plate on top of the beaker to make the process take seemingly forever, and so I arrived at a compromise of doing it with the plate on for about 80% reduction, and the rest fully open, knowing I was losing precious smells, but really no choice unless I wanted it to take days. The results were really tiny amounts of some pretty nice stuff: from the 1 liter gardenia I got about 1 ml of nice goo, and from the 5 liters of frangipani about 10 mls of a very true to life (VERY sticky) concrete (which cost me $50 for the hexane alone, not to mention all the labor, equipment and electricity). Oakmoss was less of a success, I think I will go with a soxhlet extraction in ethanol directly next time (oh and the oakmoss was from my home in France, I brought it back to Burma to play with --in case anyone though I was saying there is oakmoss in Burma) The next step to make an absolute is to stir up the concrete in ethanol and then rotovap out the ethanol to get an absolute. This is (mostly) unnecessary for personal use (and I had no way of doing it anyway) and I just mixed the concrete in ethanol and filtered (many weeks later) and keep the ethanol concrete "tincture" for use directly as is. It was messy, time consuming, hard, dangerous and expensive, but I have moved from Burma now, and I treasure these concretes more than almost anything in my collection.

I am not recommending anyone replicate what I did, but hopefully me experience will help others.

Re: Making an Absolute - Process, lessons learned, and recommendations

Re: Making an Absolute - Process, lessons learned, and recommendations

That was an interesting read, gecko. Evaporation of hexane or alcohol is indeed difficult without a vacuum pump. I'll run through one of the more basic methods that I have used in the past to produce concretes, without the addition of any heat. The key is in selecting the right solvent for the job. Butane is a simple alkane, like hexane but boils at -0.5°C and it can therefore be removed from the concrete without the addition of heat or a vacuum.

Method:

1) Loosly fill a 1 liter stainless steel thermos flask with fresh, separated but unground botanicals.
2) Place the thermos flask in a freezer overnight, along with three canisters of high purity butane lighter refill (Colibri, Newport, Vector etc.)
3) Remove from the freezer and take outdoors, for good ventilation.
4) Place a metal jar lid with a puncture hole in the centre, over the mouth of the thermos flask.
5) Put on protective gloves, as a precaution.
6) Insert the nozzle of the butane canister into the hole in the lid and inject the butane down into the thermos flask. Repeat with second canister and the third if necessary. The botanicals must be fully submerged in the butane. After inspection, place the jar lid back on loosely.
7) Leave the thermos flask to sit in the shade for 2 hours or more, sheltered from wind.
8) Slowly pour the butane through a fine stainless steel strainer, into a borosilicate glass, pyrex or stainless steel dish.
9) Leave the butane to evaporate in the dish for about half an hour or so, or until only a viscous or solid residue remains.
10) Bring indoors and leave to finish curing at room temperature for atleast 24 hours.
11) Scrape up the cured concrete from the dish and place in suitable glass vessels. You have now produced a high quality concrete, undegraded by any heat.

Optional extra:

12) Dissolve the concrete in ethanol, refrigerate at -18°C or lower for 24-48 hours (winterization) and filter out the wax/fats with lab grade filter paper or coffee filter paper. Bottle and use as a winterized tincture.

Important: Do not attempt solvent extractions unless you understand all of necessary safety protocols.

Re: Making an Absolute - Process, lessons learned, and recommendations

The butane extraction method sounds interesting, but isn't ethyl mercaptan usually added to make it smell like 'gas'?

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Originally Posted by pkiler

What about a hand vacuum pump?

I bought one on ebay a few years back...

A hand vacuum pump should work, but you'll have to keep pumping. You might like to apply a little heat to help things along - a warm water bath (NO FLAMES!!!) would be ideal - but there are complications...

The normal procedure for boiling under vacuum is to lower the pressure first, then control boiling using the heat source. But as you're using a hand pump the pressure will vary (unless your pump has a regulator) so the boiling point will vary. This can lead to gentle simmering suddenly switching to instant vaporisation in your vacuum vessel, and all your liquid - including the things you want to keep - ending up in your pump. An air leak line into the liquid might help here, but I'm guaranteeing NOTHING...

And don't forget that you'll have inflammable vapour flowing through your pump.

Re: Making an Absolute - Process, lessons learned, and recommendations

Originally Posted by Skelly

The butane extraction method sounds interesting, but isn't ethyl mercaptan usually added to make it smell like 'gas'?

Hi Skelly, yes it is often added to larger tanks intended for cooking or heating, to aid in the detection of gas leaks. Some of the cheaper butane lighter refill canisters contain this butane aswel. However, the higher end butane lighter refills tend to use butane without any ethyl mercaptan added. The brands that you should look out for are Colibri, Newport, Vector, London and any other brand that states that it is triple refined or more, or has the "Near Zero Impurities" logo on the can.

Re: Making an Absolute - Process, lessons learned, and recommendations

Sorry for the delay in responding to all the incredible posts here, it's been a busy few weeks for me. I think this is now the most detailed, instructional, and useful page on homemade absolutes I have been able to find online. I also thank everyone for the safety precautions as I would hate for anyone inexperienced in handling these dangerous chemicals get injured in the process.

Lucky for me I really enjoyed chemistry in both college and high school, and spent some time working in an chem lab surrounded by many of these exact chemicals, and am greatly familiar with their risks from hands on experience. Unfortunately it has been very difficult to locate a local supplier of hexane. So far, my only option is Fisher Scientific via their online store where 4 liters is approximately 180 USD. I may attempt the butane method as those materials are readily available to me.

I do have one follow up question, why should you only use fresh ingredients? Does the process not work successfully with dried plants (either hexane or butane method), or is it a matter of quality?

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Also, aside from my question from my previous post regarding fresh v. dried materials, I have a question about the vacuum process for hexane. I believe this may have been touched on before, but I wanted to confirm that my thinking is correct. Upon subjecting the hexane/plant mixture to a vacuum, the hexane is able to boil off at a temp lower than it's atmospheric pressure boiling point of 68-69 degree celsius, thus avoiding the need to apply heat to the mixture, and avoiding excessive loss of fragrance volatiles. First, is collecting the boiled hexane back in a liquified state (since this is essentially distillation) result in re-usable hexane, or will it be tainted slightly with oils that also evaporated (only reusable for the same type of plant matter, or not recommended for reuse period)?

Also, from a chemistry standpoint, why (besides safety) is there a benefit to using the vacuum method instead of heating the hexane? If the point is to save fragrance oil, wouldn't the decreased pressure also increase the rate at which the oils themselves also evaporated? Is it that the oils are particularly sensitive to heat resulting in a change of odor where pressure does not affect the odor? Thanks again for all the help. This thread has been an amazing resource.

Re: Making an Absolute - Process, lessons learned, and recommendations

Originally Posted by ksennish

I do have one follow up question, why should you only use fresh ingredients? Does the process not work successfully with dried plants (either hexane or butane method), or is it a matter of quality?

It does work with dried plant material aswel but absolutes have historically been made from concretes rather than oleoresins. Concretes are extracted from fresh plant material with non-polar solvents. They are often favored in the perfume industry because of their fresher aroma but the non-polar solvents used to make concretes extract alot of plant waxes. These waxes don't dissolve in alcohol or water so they are removed before the extract is added to fragrances. There is no reason why you can't make an oleoresin from dried material and then make an alcohol extraction. It just wouldn't technically be called an absolute.

Originally Posted by ksennish

Also, aside from my question from my previous post regarding fresh v. dried materials, I have a question about the vacuum process for hexane. I believe this may have been touched on before, but I wanted to confirm that my thinking is correct. Upon subjecting the hexane/plant mixture to a vacuum, the hexane is able to boil off at a temp lower than it's atmospheric pressure boiling point of 68-69 degree celsius, thus avoiding the need to apply heat to the mixture, and avoiding excessive loss of fragrance volatiles. First, is collecting the boiled hexane back in a liquified state (since this is essentially distillation) result in re-usable hexane, or will it be tainted slightly with oils that also evaporated (only reusable for the same type of plant matter, or not recommended for reuse period)?

It can be re-used but if you notice any unwanted aroma in the hexane, you can fractionally distill it. You should know how to do that with your chemistry background. If you wish to recapture butane, you will need a spare gas tank and a pump but it's complicated. Alternatively, you can pour the butane from one thermos onto fresh plant material in a second pre-chilled thermos.

Originally Posted by ksennish

Also, from a chemistry standpoint, why (besides safety) is there a benefit to using the vacuum method instead of heating the hexane? If the point is to save fragrance oil, wouldn't the decreased pressure also increase the rate at which the oils themselves also evaporated? Is it that the oils are particularly sensitive to heat resulting in a change of odor where pressure does not affect the odor? Thanks again for all the help. This thread has been an amazing resource.

That's correct, it is to protect the more delicate aromas from deterioration. I hope that this has helped to answer your questions.

Re: Making an Absolute - Process, lessons learned, and recommendations

Thanks! Your response is much appreciated. I'm hoping to attempt the butane method in the next week or so, and then hopefully locate some hexane to attempt that later on, once I've gathered the appropriate equipment.

Re: Making an Absolute - Process, lessons learned, and recommendations

Ksennish, if you choose to use dry plant material, you can grind it up before extracting with butane. You wouldn't want to grind up fresh, water rich plant material when using butane because the butane would freeze it together in a clump and prevent extraction. If you grind up the dry material, you'll need to filter through lab or coffee filter paper. If you don't have a stainless steel or lab glass funnel, you can fashion a filter holder by bending a wire coat hanger into a loop with a handle and then fit the filter paper into the loop and clamp it around the edges with some clothes pegs.

Re: Making an Absolute - Process, lessons learned, and recommendations

Hello to everyone and thanks to all those who have shared such valuable information and experience. Ksennish, have you made any recent progress with this project? I am wondering if anyone can tell me what solvents, other than ethanol, could be used to process an absolute from a concrete. Would other alcohols work as well?
Also, I have sampled some oils that were distilled from concretes, presumably using some form of hydrodistillation, and have read of some others being done with molecular distillation. Can anyone comment on whether a rotovap could be used for this sort of a process?
Finally, the butane extractions mentioned above, could this be used to obtain an absolute from a concrete?
Thanks in advance for your help,

Re: Making an Absolute - Process, lessons learned, and recommendations

Originally Posted by Scentifolia

Hello to everyone and thanks to all those who have shared such valuable information and experience. Ksennish, have you made any recent progress with this project? I am wondering if anyone can tell me what solvents, other than ethanol, could be used to process an absolute from a concrete. Would other alcohols work as well?
Also, I have sampled some oils that were distilled from concretes, presumably using some form of hydrodistillation, and have read of some others being done with molecular distillation. Can anyone comment on whether a rotovap could be used for this sort of a process?
Finally, the butane extractions mentioned above, could this be used to obtain an absolute from a concrete?
Thanks in advance for your help,

Others here have more experience than I do in making extractions - I just use them - however I can add a little more to the sum of knowledge here: ethanol is, by definition, the only solvent you can use to get from a concrete to an absolute. The reason I say that is because the point of creating the absolute is to exclude all those things that are not soluble in ethanol. Another solvent would not ensure this.

Distillation from a concrete would rather defeat the point of hydrocarbon extraction, which is to avoid the changes in the volatiles that occur with the application of significant heat. Perhaps cold, vacuum distillation might be effective? I’m afraid I’m at the limits of my knowledge now . . .

Butane extractions are commercially called Butaflors - a patented process - where the butane is used to extract the concrete, which is then extracted in ethanol to remove the non-ethanol soluble elements (mainly plant wax). Using butane to extract a concrete extracted with, say hexane, would result in a (different) concrete, not an absolute. My post on extraction methods and terminology for natural materials may help you get your head around the differences.

Finally I should just point out that, at least with some materials, grinding up the plant vs keeping it whole can radically alter the resulting oil because the grinding process allows chemicals in the plant that are normally kept separated by the cells to come into contact with each other and react prior to extraction. A case in point here is cilantro - the oil extracted from coriander leaves - modern thinking is that the main reason for the differences between one cilantro and another (besides all the usual things such as climate, season and degree of adulteration) is the degree of damage the plant experiences prior to extraction. In this case the aldehydes that are characteristic of this oil can be converted into alcohols by enzymes they are not normally exposed to in the plant - the more chopping up the less aldehydes - thus destroying what you are trying to extract. I’m not aware of detailed research on plants other than coriander but it seems likely that similar effects might occur.

Re: Making an Absolute - Process, lessons learned, and recommendations

Thanks Chris, that is very helpful. To put my questions into context, let me explain the challenge. Many of my potential end users avoid alcohol based products for ritual purity reasons, and this includes those that have come into contact with ethanol or methanol, such as an absolute, even though there are perhaps only a few ppm remaining. Needless to say I am thus limited to oil based perfumes. To work around this, I have in the past, commissioned a few different extractions from floral concretes, Co2 and distillation, but the former, while decent, was kind of like half concrete and half absolute in consistency. The latter seems to have suffered a lot of thermal degradation with a lot of loss of precious top notes and heart notes. What has renewed my interest in this is the description (from Robertet) that follows:

Jasmine Abs. DM
Molecular distillation without solvents on Egyptian Grandiflorum Jasmine concrete. This process enables to keep the most volatile notes lost in traditional transformation from concrete into absolute. Odour: Floral, fruity, type jasmine benzol, fresh and green closed to the original jasmine flower scent.

I have read up on molecular distillation and wiped film units a bit and have quite a few questions about the differences between them and standard vacuum distillation, in particular with regards to the idea of distilling a concrete. Can the temperature of distillation with a standard vacuum distillation unit or even a rotovap be reduced enough to avoid thermal degradation?

Alternatively, since the extract does not need to be soluble in ethanol anyway, is there a way of rendering a concrete liquid even if a portion of the waxes etc remain?

Sorry for the long post, any insights, suggestions or resources are eagerly awaited and highly valued,
Many thanks

Re: Making an Absolute - Process, lessons learned, and recommendations

Originally Posted by Scentifolia

Thanks Chris, that is very helpful. To put my questions into context, let me explain the challenge. Many of my potential end users avoid alcohol based products for ritual purity reasons, and this includes those that have come into contact with ethanol or methanol, such as an absolute, even though there are perhaps only a few ppm remaining. Needless to say I am thus limited to oil based perfumes. To work around this, I have in the past, commissioned a few different extractions from floral concretes, Co2 and distillation, but the former, while decent, was kind of like half concrete and half absolute in consistency. The latter seems to have suffered a lot of thermal degradation with a lot of loss of precious top notes and heart notes. What has renewed my interest in this is the description (from Robertet) that follows:

Jasmine Abs. DM
Molecular distillation without solvents on Egyptian Grandiflorum Jasmine concrete. This process enables to keep the most volatile notes lost in traditional transformation from concrete into absolute. Odour: Floral, fruity, type jasmine benzol, fresh and green closed to the original jasmine flower scent.

I have read up on molecular distillation and wiped film units a bit and have quite a few questions about the differences between them and standard vacuum distillation, in particular with regards to the idea of distilling a concrete. Can the temperature of distillation with a standard vacuum distillation unit or even a rotovap be reduced enough to avoid thermal degradation?

Alternatively, since the extract does not need to be soluble in ethanol anyway, is there a way of rendering a concrete liquid even if a portion of the waxes etc remain?

Sorry for the long post, any insights, suggestions or resources are eagerly awaited and highly valued,
Many thanks

OK, I understand the problem. I’m afraid most of it is beyond my expertise, but I can suggest that, in my experience, many CO2 extractions and other difficult materials can be successfully dissolved in IPM or TEC: I have not tried dissolving a concrete directly in one of these solvents but it might well work and is probably worth a try.

Failing that, why not make a solid perfume, using the concrete as a basis? I’ve experimented with that using orange flower concrete with some success, though I have yet to render a commercially viable product from it, you might well find it more worthwhile given the different constituency you are addressing.

Re: Making an Absolute - Process, lessons learned, and recommendations

Hi, I am new to basenotes. I have access to many concretes and i am interested in developing absolutes from them. Arctander suggests using a vacuum pump to remove the alcohol from the solution. Has anyone done this before? I am looking into buying a vacuum pump but i'm unsure as to which type of pump would be the best for this procedure. Any advice would be much appreciated.
Thank you

Re: Making an Absolute - Process, lessons learned, and recommendations

You can remove the alcohol with a vacuum pump sealed Rotovap, or possibly by vacuum pumping through a filter on a buechner funnel.

Kinda depends upon how much you want to process, and how much money you have to throw at it. And if you have the skill and space to set up and run a rotovap. A rotovap, glassware, heated water tank, and vacuum pump can easily run into thousands of dollars. A hand vacuum pump, vacuum flask, and beuchner funnel can likely be had on Ebay for under $100. (and tired hands...)

Re: Making an Absolute - Process, lessons learned, and recommendations

On dry material one can try DME extraction.
I'm using a commercial extractor, basically an aluminium pipe, from a Swiss manufacturer in order to get a very nice vanilla concrete.
The yield amounts to 10ml of the semiliquid vanilla concrete from 100g of vanilla powder.
DME, dimethyl ether, boils at -39 Celsius so no vacuum pump is needed.